There are a number of factors which influence the dimensional accuracy of a workpiece which can be achieved in a turning operation. Illustrative of such factors, are: the accuracy of the mechanisms which control machine tool slide movement; the deformation of the machine tool and the workpiece due to cutting force; the heat generated during cutting; and the extent of tool wear. The prior art has recognized that the aforementioned unpredictable factors are not susceptible to effective operator monitoring and in response has provided laser optical devices adapted to generate beams which impinge on the periphery of a workpiece, such as shown in U.S. Pat. Nos. 3,749,500 and 3,812,376. Such prior are systems have a drawback in that they require positioning units which can be relatively complex. In addition, such systems do not offer the many advantages of laser interferometry.
Currently, some numerically controlled machine tools employ laser interferometry to precisely position the slides of the machine to obtain superior resolution. Typically such systems embody a laser source and one or more receivers, interferometer and retroflector sets. However, laser interferometry has not been adapted to directly measure the dimensions of a turned workpiece.